Formation of Amorphous Calcium Carbonate Thin Films and Their Role in Biomineralization

A new and simple method for preparing large-area and continuous calcium carbonate films under mild conditions is described. Amorphous calcium carbonate (ACC) films have been formed both in the presence and absence of a poly(acrylic acid) inhibitor. The transformation from ACC to crystalline vaterite/calcite has been observed by optical microscopy and confirmed by external reflection infrared spectroscopy. We have shown that the inhibiting effects of substrates and inhibitors on the transformation of ACC result in the formation of good CaCO3 films. From our results, we suggested that ACC precipitates are initially formed from highly supersaturated solutions, which then deposit as films through the cooperation between an insoluble matrix and a soluble inhibitor. The matrix and inhibitor were also found to affect the growth, morphology, and structure of CaCO3 crystal by influencing the phase transformation of ACC into crystalline forms. It has been shown that ACC plays an important role in the biomineralization and crystallization of calcium carbonate.